A two-dimensional model has been developed for the interfacial thermal stresses in short and long trilayer assemblies under both plane stress and plane strain conditions. Interfacial stresses are approximated using a combination of exact elasticity solutions and elementary strength of materials theories. Governing differential equations are linearized through a finite difference discretization procedure. The conditions of zero shear stress at the free edges and self-equilibrated peel stresses are satisfied. The approach is mathematically straightforward, can be extended to include inelastic behavior, and can be adapted to problems involving external loads and a variety of geometries. The results have been compared to available data in the literature and finite element analysis.